1. Field of the Invention
The present invention relates to a tuner, a broadcast signal processing apparatus and method. More particularly, the present invention relates to a tuner, a broadcast signal processing apparatus and method, which satisfy reception sensitivity of both terrestrial and cable televisions (TVs) when selecting a broadcast signal through a single conversion tuner.
2. Description of the Related Art
As shown in FIG. 1, a conventional single conversion type tuner having a three band configuration comprises an input tuning filter 4 having a very high frequency low (VHFL) filter 1 to pass a VHF-low frequency band of a received broadcast signal; a very high frequency high (VHFH) filter 2 to pass a VHF-high frequency band of the received broadcast signal; and a ultra high frequency (UHF) filter 3 to pass a UHF band of the received broadcast signal; a signal amplifier 5 having a plurality of MOSFETs F1, F2 and F3 to amplify the signal output from the VHFL filter 1, VHFH filter 2 and UHF filter 3, according to a predetermined amplification degree; an inter-stage tuning filter 9 to filter a frequency of a broadcast signal of a desired channel among signals which are amplified and output from the signal amplifier 5; and a signal converter 10 to convert the signal output from the inter-stage tuning filter 9 into a predetermined intermediate frequency (IF) signal.
In the conventional single conversion tuner, as the input tuning filter 4 and the inter-stage tuning filter 9 comprise a tracking filter, channel distortion is relatively small and noise figure is excellent, though a difference of signal intensity is excessive between channels. Thus, the conventional single conversion tuner is suitable for receiving terrestrial television (TV) broadcast signals.
More signals in the cable TV broadcast environment exist than in the terrestrial broadcast environment. If the single conversion tuner is used in the cable TV environment, harmonic components, which are generated when the signal is amplified, are poorly eliminated due to nonlinear property of the MOSFETs F1, F2 and F3, thereby deteriorating the signal and damaging a picture.
Thus, a double conversion type tuner (not shown) is generally used in the cable TV environment. The double conversion type tuner is excellent in elimination of the harmonic components when the signal is amplified. However, the conventional double conversion type tuner (not shown) is low in the noise figure, thereby lowering picture quality when the terrestrial TV broadcast signal is received. Also, the double conversion type tuner is more expensive than the signal conversion tuner.